I'll agree with Darin, the knobs are to keep the lens mount and camera mount
boards from coming off. You do remove the screw at the end of the rail nearest
the lens board so you can pull it off the rail and reverse it.
I am wondering why the put the screw stops at both ends rather than just have a
non-removable stop built in to one end, the end with the camera mount board.
It may be as simple that it's cheaper to drill and tap a hole and put a knob on
the end than to mill a stop into the rail.
I checked on Alan Wood's site
http://www.alanwood.net/photography/olympus/auto-bellows.html
and on the mir site:
http://www.mir.com.my/rb/photography/hardwares/classics/olympusom1n2/shared/macr
o/index1.htm
Both do not indicate any use of those threaded holes other than what we are
guessing.
But I did learn that (according to the MIR site) that the boards are threaded
for Series VI filters. I don't have that filter (and why wouldn't they use 49mm
filter thread?) - so I can't verify that tidbit of information. I see ridges
but I couldn't say for certain that they are threads or just ridges to knock
down reflected light.
But back to the original premise of the show, just how much extension do you
need Wayne? Take a cine lens and reverse it on a bellows. Gobs and gobs of
magnification. No depth of field but magnification galore.
Jay - still aspiring to take a good picture.
>Wayne, I'm by no means an expert on OM gear, but I know of no accessories that
>screw into the ends of the focusing rail. Their only purpose to my knowledge
>is, as you said, to prevent the standards from falling off the ends.
>If in fact the threads are an american standard thread, which I highly doubt
>since they were made in Japan, and are not 1/4-20, the finer 1/4 inch thread is
>1/4-28. My guess, just from glancing at them, is that they're either 5mm or
>6mm. Unless someone else happens to know off-hand, I work at a machine shop and
>can take mine to work this evening and check to find out for sure.
>
>As to mating two rails together, physically it could be done with a simple stud
>of the proper size. However, unless I misunderstand your question, this
>wouldn't be very practical since the rack gears don't extend fully to the ends
>of the rail. Therefore you'd end up with about a 1" gap between gears,
>resulting in the standards sliding freely along the rail.
>
>Hope that helps,
>Darin
>Wayne Harridge wrote:
>>At each end of the rail of the OM bellows there is thumb screw which stops
>>the bellows standards falling off the end of the rail.
>>Were there any accessories that also screwed into these holes in the end of
>>the rail ?
>>The threaded holes appear to be about 1/4" diameter but finer than 20tpi so
>>a standard tripod screw cannot be screwed in. What is the thread size for
>>these holes ?
>>Is it possible to join 2 sets of bellows together for extra extension ?
Hand me my costume
Please won't you pass me my mask
I have appointments I must keep with my past.
Bill Nelson - Beauty Secrets
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